Preheat the oven to 250 degrees F. Cut the polenta into 2×1-inch pieces. In a large, heavy skillet, heat the remaining ½ cup of oil over a medium-high flame. Working in batches, fry the polenta pieces until golden brown on all sides, about 3 minutes per side. Using tongs, transfer the polenta pieces to paper towels and drain. Place the polenta pieces on a baking sheet and keep warm in the oven while cooking the remaining batches.